<HTML
><HEAD
><TITLE
>Floppies</TITLE
><META
NAME="GENERATOR"
CONTENT="Modular DocBook HTML Stylesheet Version 1.63
"><LINK
REL="HOME"
TITLE="The Linux System Administrator's Guide"
HREF="index.html"><LINK
REL="UP"
TITLE="Using Disks and Other Storage Media"
HREF="c955.html"><LINK
REL="PREVIOUS"
TITLE="Hard disks"
HREF="x1001.html"><LINK
REL="NEXT"
TITLE="CD-ROMs"
HREF="x1057.html"></HEAD
><BODY
CLASS="SECT1"
BGCOLOR="#FFFFFF"
TEXT="#000000"
LINK="#0000FF"
VLINK="#840084"
ALINK="#0000FF"
><DIV
CLASS="NAVHEADER"
><TABLE
WIDTH="100%"
BORDER="0"
CELLPADDING="0"
CELLSPACING="0"
><TR
><TH
COLSPAN="3"
ALIGN="center"
>The Linux System Administrator's Guide: Version 0.7</TH
></TR
><TR
><TD
WIDTH="10%"
ALIGN="left"
VALIGN="bottom"
><A
HREF="x1001.html"
>Prev</A
></TD
><TD
WIDTH="80%"
ALIGN="center"
VALIGN="bottom"
>Chapter 6. Using Disks and Other Storage Media</TD
><TD
WIDTH="10%"
ALIGN="right"
VALIGN="bottom"
><A
HREF="x1057.html"
>Next</A
></TD
></TR
></TABLE
><HR
ALIGN="LEFT"
WIDTH="100%"></DIV
><DIV
CLASS="SECT1"
><H1
CLASS="SECT1"
><A
NAME="AEN1042"
>6.3. Floppies</A
></H1
><P
>A floppy disk consists of a flexible membrane covered on one
	or both sides with similar magnetic substance as a hard disk. The
	floppy disk itself doesn't have a read-write head, that is included
	in the drive.  A floppy corresponds to one platter in a hard disk,
	but is removable and one drive can be used to access different
	floppies, and the same floppy can be read by many drives, whereas
	the hard disk is one indivisible unit.</P
><P
>Like a hard disk, a floppy is divided into tracks and sectors
	(and the two corresponding tracks on either side of a floppy
	form a cylinder), but there are many fewer of them than on a
	hard disk.</P
><P
>A floppy drive can usually use several different types of disks;
	for example, a 3.5 inch drive can use both 720 kB and 1.44 MB disks.
	Since the drive has to operate a bit differently and the operating
	system must know how big the disk is, there are many device files
	for floppy drives, one per combination of drive and disk type.
	Therefore, <TT
CLASS="FILENAME"
>/dev/fd0H1440</TT
> is the first floppy 
	drive (fd0), which must be a 3.5 inch drive, using a 3.5 inch, high
	density disk (H) of size 1440 kB (1440), i.e., a normal 3.5 inch HD
	floppy.
	</P
><P
>The names for floppy drives are complex, however, and Linux
	therefore has a special floppy device type that automatically
	detects the type of the disk in the drive.  It works by trying to
	read the first sector of a newly inserted floppy using different
	floppy types until it finds the correct one. This naturally requires
	that the floppy is formatted first. The automatic devices are called
	<TT
CLASS="FILENAME"
>/dev/fd0</TT
>, <TT
CLASS="FILENAME"
>/dev/fd1</TT
>, and so 
	on.</P
><P
>The parameters the automatic device uses to access a disk can
	also be set using the program <B
CLASS="COMMAND"
>setfdprm</B
>.  This can
	be useful if you need to use disks that do not follow any usual
	floppy sizes, e.g., if they have an unusual number of sectors, or if
	the autodetecting for some reason fails and the proper device file is 
	missing.</P
><P
>Linux can handle many nonstandard floppy disk formats
	in addition to all the standard ones.  Some of these require using
	special formatting programs.  We'll skip these disk types for now,
	but in the mean time you can examine the
	<TT
CLASS="FILENAME"
>/etc/fdprm</TT
> file.  It specifies the settings
	that <B
CLASS="COMMAND"
>setfdprm</B
> recognises.</P
><P
>The operating system must know when a disk has been changed in
	a floppy drive, for example, in order to avoid using cached data
	from the previous disk.  Unfortunately, the signal line that is used
	for this is sometimes broken, and worse, this won't always be
	noticeable when using the drive from within MS-DOS. If you are
	experiencing weird problems using floppies, this might be the
	reason.  The only way to correct it is to repair the floppy drive.</P
></DIV
><DIV
CLASS="NAVFOOTER"
><HR
ALIGN="LEFT"
WIDTH="100%"><TABLE
WIDTH="100%"
BORDER="0"
CELLPADDING="0"
CELLSPACING="0"
><TR
><TD
WIDTH="33%"
ALIGN="left"
VALIGN="top"
><A
HREF="x1001.html"
>Prev</A
></TD
><TD
WIDTH="34%"
ALIGN="center"
VALIGN="top"
><A
HREF="index.html"
>Home</A
></TD
><TD
WIDTH="33%"
ALIGN="right"
VALIGN="top"
><A
HREF="x1057.html"
>Next</A
></TD
></TR
><TR
><TD
WIDTH="33%"
ALIGN="left"
VALIGN="top"
>Hard disks</TD
><TD
WIDTH="34%"
ALIGN="center"
VALIGN="top"
><A
HREF="c955.html"
>Up</A
></TD
><TD
WIDTH="33%"
ALIGN="right"
VALIGN="top"
>CD-ROMs</TD
></TR
></TABLE
></DIV
></BODY
></HTML
>